Posts Tagged ‘Distributed File System (DFS)’

Social networking sites are building huge online communites of people sharing interests & activities. Social networking sites allows individuals to meet strangers which makes it unique. After joining a social network site, users are prompted to identify others in the system with whom they have a relationship. The label for these relationships differs depending on the site—popular terms include “Friends,” “Contacts,” and “Fans.” Most SNSs also provide a mechanism for users to leave messages on their Friends’ profiles. This feature typically involves leaving “comments,” although sites employ various labels for this feature. In addition, SNSs often have a private messaging feature similar to webmail. While both private messages and comments are popular on most of the major SNSs, they are not universally available.

Social networking has created new ways to communicate and share information. Social networking websites are being used regularly by millions of people, and it now seems that social networking will be an enduring part of everyday life.

You are about to start the installation process of the OSSEC HIDS.
You must have a C compiler pre-installed in your system.
If you have any questions or comments, please send an e-mail
to dcid@ossec.net (or daniel.cid@gmail.com).

- The configuration can be viewed or modified at /var/ossec/etc/ossec.conf

Thanks for using the OSSEC HIDS.
If you have any question, suggestion or if you find any bug,
contact us at contact@ossec.net or using our public maillist at
ossec-list@ossec.net
(http://mailman.underlinux.com.br/mailman/listinfo/ossec-list).

As you might have seen during OSSEC HIDS installation, the installer also created the necessary system startup links for OSSEC HIDS, so that OSSEC HIDS will be started automatically whenever you boot/reboot your system.

After OSSEC HIDS has been started, it will run silently in the background, performing log analysis, integrity checking, rootkit detection, etc. You can check that it’s running by executing

———————————————————————–
ERROR: Mrtg will most likely not work properly when the environment
variable LANG is set to UTF-8. Please run mrtg in an environment
where this is not the case. Try the following command to start:

env LANG=C /usr/bin/mrtg /etc/mrtg/mymrtg.cfg

9) env LANG=C /usr/bin/mrtg /etc/mrtg/mymrtg.cfg (you will get following output)

10) Point your browser to http://192.168.5.2/mymrtg/192.168.5.2_2.html.

LZO – Lempel-Ziv-Oberhumer is a lossless data compression algorithm that is focused on decompression speed. It is a portable lossless data compression library written in ANSI C. It offers pretty fast compression and *very* fast decompression. Decompression requires no memory. In addition there are slower compression levels achieving a quite competitive compression ratio while still decompressing at this very high speed.

Dumping a cupboard-full of documents, audio cassettes, video tapes and even photo albums on a hard drive or DVD might sound easy, but is actually a complex process. Operating systems use logical data structures for storing, organizing and keeping track of files on a partition or on an optical disc, called a Filesystem. The basic function of a FileSystem is to make efficient use of disk space for data storage, ease basic file operations (read, write, copy and delete) and catalogue files for faster retrieval.

A disk partition is like a compartment in a train, while the Filesystem is the seating arrangement fixed within the compartments. Before using any partition on a disk, a logical Filesystem needs to be initialized on it. Let’s have a look at how a typical Filesystem works.

How Filesystems Work?

The space in a hard drive is divided into units called sectors, usually of 512 bytes. The Filesystem groups the sectors together after creating a sector index; the group is called a cluster or an allocation unit. It’s difficult for the Filesystem to deal with data on a sector-by-sector basis, so when the Filesystem needs to access a sector for a read-write operation, it will first define the cluster number of that sector. Then from that cluster, it will use the sector index to access that particular sector. Each logical volume (hard drive) has a table—called the File Allocation Table (FAT)—that carries all the information about the sectors and the files stored on those sectors.

Types of Filesystems

Disk-based FilesystemsThese would be found on hard disks, CD-ROMs and DVDs. Files are stored in a sequence of bytes on fixed-sized blocks called sectors; these Filesystems feature random-access file reads and writes, and also file fragmentation across the disk. Some disk-based Filesystems also have journaling and versioning. In a Journaling Filesystem like XFS on the Silicon Graphics platform, changes in files are logged first in a specially allocated area called a Journal before they’re actually written on the main Filesystem. Versioning Filesystems like OpenVMS allow for the existence of several versions of the same file, and take periodic backups. Popular disk-based Filesystems include:

Solid-state media Filesystems: These are designed for storing files on devices that rely on Flash memory as their storage. Such Filesystems require special handling, because data blocks wear out if information is repetitively written and rewritten on the drive. Besides, the blocks have to be erased explicitly before any data is written on them. The Journaling Flash Filesystem (JFFS) and Yet Another Flash Filesystem (YAFFS) are popular solid-state Filesystems.

Record-oriented Filesystems: The basic purpose of such Filesystems is to store files in the form of records to be compatible with older operating systems that are used exclusively on mainframes and minicomputers.

Shared-disk Filesystem: These are also known as SAN (Storage Area Network) Filesystems or Cluster Filesystem. As the name suggests, they are used on huge blocks of storage which are directly accessible to computers via a network connection.

Network FilesystemsNetwork Filesystems (or distributed Filesystems) support the sharing of files, printers and other computing resources over a network. The performance of such Filesystems is measured by the time it requires to satisfy the service requests by different computers connected on the network. Such Filesystems are found on file-servers and provide access to files by acting as clients for remote access protocols like NFS (Network Filesystem) or SMB (Server Message). NFS and SMB are popular examples of network Filesystems. Several network Filesystems prevail today: 9P, Apple Filing Protocol (AFP), NetWare Core Protocol (NCP), Coda, Distributed File System (DFS) and Google File System (GFS), to name a few.

Filesystems are critical for storage media to run properly with the operating system. Regular maintenance and protection from malware is not only advisable, it’s necessary.